Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L21/00—Compositions of unspecified rubbers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L7/00—Compositions of natural rubber
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
  • C08L9/06—Copolymers with styrene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
  • C08K3/20—Oxides; Hydroxides
  • C08K3/22—Oxides; Hydroxides of metals
  • C08K2003/2296—Oxides; Hydroxides of metals of zinc
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/30—Sulfur-, selenium- or tellurium-containing compounds
  • C08K2003/3045—Sulfates
  • C08K2003/3063—Magnesium sulfate
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K2201/00—Specific properties of additives
  • C08K2201/002—Physical properties
  • C08K2201/003—Additives being defined by their diameter
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K2201/00—Specific properties of additives
  • C08K2201/002—Physical properties
  • C08K2201/004—Additives being defined by their length
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/02—Elements
  • C08K3/06—Sulfur
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/34—Silicon-containing compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
  • C08K5/0025—Crosslinking or vulcanising agents; including accelerators

Definitions

• the present invention relates to a rubber composition comprising an inorganic fiber material and a tire having an internal member formed of the rubber composition.
• Patent Document 1 A technique of giving anisotropy to a modulus of a rubber by compounding a bio-derived nanomaterial such as a cellulose fiber into a tire member is known (for example, Patent Document 1).
• Patent Document 1 JP 5691463 B
• a rubber is strengthened by forming a network structure and that anisotropy becomes easy to be obtained in a fiber material.
• a dispersed state of the fiber material in a rubber matrix is poor, the fiber materials aggregate, making it difficult to obtain anisotropy, and a sufficient reinforcing property with respect to the rubber matrix cannot be obtained, and therefore it is considered that breaking strength is also lowered.
• a rubber composition comprising a conventional fiber material has a high elastic modulus, and currently, a market demand value cannot have been sufficiently met in ride comfort and vibration.
• the present invention relates to:
• a rubber composition highly achieving both breaking strength and anisotropy is provided by compounding an inorganic fiber material and a coupling agent. Moreover, the tire comprising the tire internal member formed of the rubber composition has improved ride comfort and steering stability with a good balance.
• the rubber composition of the present disclosure comprises a rubber component, an inorganic fiber material, and a coupling agent, it exhibits excellent breaking strength and anisotropy.
• an inorganic fiber material By compounding an inorganic fiber material into the rubber composition, a modulus of the rubber can be given with anisotropy, but it is considered that the inorganic fiber material is less likely to be dispersed in the rubber component compared with a filler such as carbon black. Therefore, the entire rubber matrix cannot be reinforced, and it is considered that it is difficult to obtain sufficient breaking strength and anisotropy.
• a coupling agent together with the inorganic fiber material dispersibility of the inorganic fiber material in the rubber matrix is improved to reinforce the entire matrix, and it becomes possible to orient the inorganic fiber material in a uniform state, and therefore it is considered that anisotropy also becomes improved.
• the value of the ratio of 100% modulus in the grain direction M100a to 100% modulus in the cross-grain direction M100b as the index of anisotropy (M100a/M100b, may be herein referred to as the "modulus ratio") is 1.10 or more, more preferably 1.15 or more, further preferably 1.20 or more, from the viewpoint of an excellent anisotropy.
• an upper limit value of the ratio of the modulus is not particularly limited, but is usually 2.00 or less, and may be 1.80 or less, 1.60 or less, or 1.50 or less.
• the ratio of the modulus By setting the ratio of the modulus to 1.10 or more, a supple response to the cross-grain direction of the inorganic fiber material oriented in a highly dispersed state with the coupling agent is realized, and rigidity in the grain direction is increased, allowing for improvement in responsiveness.
• the "grain direction” means a rolling direction when a sheet is formed by extrusion or shearing, while the "cross-grain direction” means a direction perpendicular to the grain direction.
• the grain direction of the inorganic fibers may be any of a circumferential direction, a radial direction, and a width direction of the tire, but it is preferably arranged along the tire circumferential direction from the viewpoint of improving ride comfort and steering stability with a good balance.
• Examples of the rubber component that can be used in the present disclosure include diene-based rubbers such as an isoprene-based rubber, a styrene-butadiene rubber (SBR), a butadiene rubber (BR), a styrene-isoprene-butadiene rubber (SIBR), a chloroprene rubber (CR), and an acrylonitrile-butadiene rubber (NBR); non-diene-based rubbers such as an ethylene-propylene-diene rubber (EPDM), a butyl rubber (IIR), and a halogenated butyl rubber (X-IIR), and the like. They may be used alone, or two or more thereof may be used in combination.
• diene-based rubbers such as an isoprene-based rubber, a styrene-butadiene rubber (SBR), a butadiene rubber (BR), a styrene-isoprene-butad
• the rubber component may be a rubber component comprising at least one selected from the group consisting of an isoprene-based rubber, a SBR, and a BR, may be a rubber component comprising an isoprene-based rubber, may be a rubber component comprising an isoprene-based rubber and a BR, may be a rubber component consisting only of an isoprene-based rubber and a BR, may be a rubber component comprising a BR, may be a rubber component comprising a BR and a SBR, may be a rubber component consisting only of a BR and a SBR, may be a rubber component comprising an isoprene-based rubber, a SBR, and a BR, or may be a rubber component consisting only of an isoprene-based rubber, a SBR, and a BR.
• a content of the diene-based rubber in 100% by mass of the rubber component is preferably 60% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, particularly preferably 85% by mass or more. Moreover, it may be a rubber component consisting only of a diene-based rubber.
• an isoprene-based rubber for example, those common in the tire industry can be used, such as an isoprene rubber (IR) and a natural rubber.
• the natural rubber includes a non-modified natural rubber (NR), as well as a modified natural rubber such as an epoxidized natural rubber (ENR), a hydrogenated natural rubber (HNR), a deproteinized natural rubber (DPNR), an ultra pure natural rubber, and a grafted natural rubber, and the like.
• NR non-modified natural rubber
• EMR epoxidized natural rubber
• HNR hydrogenated natural rubber
• DPNR deproteinized natural rubber
• ultra pure natural rubber and a grafted natural rubber, and the like.
• the NR is not particularly limited, and those common in the tire industry can be used, examples of which include, for example, SIR20, RSS#3, TSR20, and the like.
• a content of the isoprene-based rubber when compounded in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, further preferably 20% by mass or more, particularly preferably 30% by mass or more, from the viewpoint of breaking strength.
• an upper limit of the isoprene-based rubber in the rubber component is, but not particularly limited to, preferably 90% by mass or less, more preferably 85% by mass or less, further preferably 80% by mass or less, particularly preferably 75% by mass or less.
• the SBR is not particularly limited, examples of which include, for example, a solution-polymerized SBR (S-SBR), an emulsion-polymerized SBR (E-SBR), modified SBRs (a modified S-SBR, a modified E-SBR) thereof, and the like.
• S-SBR solution-polymerized SBR
• E-SBR emulsion-polymerized SBR
• modified SBRs a modified S-SBR, a modified E-SBR
• a S-SBR is preferable.
• the modified SBR include a SBR modified at its terminal and/or main chain, a modified SBR coupled with tin, a silicon compound, etc. (a modified SBR of condensate or having a branched structure, etc.), and the like.
• SBR there are oil-extended type SBRs, in which an extending oil is added to adjust flexibility, and non-oil-extended type SBRs, in which no extending oil is added, both of which can be used.
• SBR include, for example, SBRs manufactured and sold by JSR Corporation, Asahi Kasei Chemicals Co., Ltd., Zeon Corporation, etc. These SBRs may be used alone, or two or more thereof may be used in combination.
• a styrene content of the SBR is preferably 15% by mass or more, more preferably 18% by mass or more, further preferably 20% by mass or more, from the viewpoint of grip performance. Moreover, it is preferably 60% by mass or less, more preferably 55% by mass or less, further preferably 50% by mass or less, from the viewpoints of polymer dispersibility and fuel efficiency. Besides, in the present specification, the styrene content of the SBR is calculated by 1 H-NMR measurement.
• a content of the SBR when compounded in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, further preferably 15% by mass or more, particularly preferably 20% by mass or more, from the viewpoint of abrasion resistance.
• an upper limit of the content of the SBR in the rubber component is, but not particularly limited to, preferably 90% by mass or less, more preferably 85% by mass or less, further preferably 80% by mass or less, particularly preferably 75% by mass or less.
• the BR is not particularly limited, and those common in the tire industry can be used such as, for example, a BR having a cis 1,4 bond content (cis content) of less than 50% (a low cis BR), a BR having a cis 1,4 bond content of 90% or more (a high cis BR), a rare-earth-based butadiene rubber synthesized using a rare-earth element-based catalyst (a rare-earth-based BR), a BR containing a syndiotactic polybutadiene crystal (a SPB-containing BR), and a modified BR (a high cis modified BR, a low cis modified BR). These BRs may be used alone, or two or more thereof may be used in combination.
• the cis 1,4 bond content of the high cis BR is preferably 95% or more, more preferably 97% or more.
• the high cis BR is compounded, low temperature characteristics and abrasion resistance can be improved.
• the high cis BR include, for example, high cis BRs manufactured and sold by Zeon Corporation, Ube Industries, Ltd., etc., JSR Corporation, etc.
• the rare-earth-based BR include, for example, rare-earth-based BRs manufactured and sold by LANXESS, etc.
• SPB-containing BR examples include those in which 1,2-syndiotactic polybutadiene crystal is chemically bonded with BR and dispersed, but not those in which the crystal is simply dispersed in the BR.
• SPB-containing BR examples include, for example, SPB-containing BRs manufactured and sold by Ube Industries, Ltd., etc.
• modified BRs examples include those obtained by adding a tin compound after polymerizing 1,3-butadiene by a lithium initiator, and further those in which the terminal of the modified BR molecule has tin-carbon bond (a tin-modified BR), a butadiene rubber (a modified BR for silica) having a condensed alkoxysilane compound at its active terminal, and the like.
• modified BRs include, for example, a tin-modified polymer manufactured by ZS Elastomer Co., Ltd., a S-modified polymer (modified for silica), and the like.
• a content of the BR when compounded in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, further preferably 15% by mass or more, further preferably 20% by mass or more, particularly preferably 25% by mass or more, from the viewpoint of abrasion resistance.
• An upper limit of the content of the BR in the rubber component is, but not particularly limited to, preferably 90% by mass or less, more preferably 85% by mass or less, further preferably 80% by mass or less, particularly preferably 75% by mass or less.
• the rubber composition according to the present disclosure comprises an inorganic fiber material.
• an inorganic fiber material By giving anisotropy in addition to strength and rigidity with the inorganic fiber material oriented in the tire circumferential direction, a supple response to an input (vibration) from the tire vertical direction during rolling is realized, and by increasing rigidity in the orientation direction (tire circumferential direction), responsiveness to the input during steering is improved.
• the inorganic fiber material that can be used in the present disclosure is not particularly limited, examples of which include, for example, a magnesium sulfate fiber, a calcium silicate fiber, a potassium titanate fiber, an aluminum borate fiber, sepiolite, a glass fiber, and the like.
• a magnesium sulfate fiber, a calcium silicate fiber, a potassium titanate fiber, an aluminum borate fiber, and sepiolite are preferable, and a magnesium sulfate fiber is more preferable.
• the above-described inorganic fiber material may be used alone, or two or more thereof may be used in combination.
• magnesium sulfate fiber a basic magnesium sulfate fiber represented by MgSO 4 ⁇ 5Mg(OH) 2 ⁇ 3H 2 O is preferable.
• calcium silicate fiber a calcium silicate fiber represented by 6CaO ⁇ 6SiO 2 ⁇ H 2 O is preferable.
• potassium titanate fiber a potassium titanate fiber represented by K 2 O ⁇ 6TiO 2 or K 2 O ⁇ 8TiO 2 is preferable.
• the aluminum borate fiber an aluminum borate fiber represented by 9Al 2 O 3 ⁇ 2B 2 O 3 is preferable.
• sepiolite sepiolite represented by Mg 8 Si 12 O 30 (OH) 4 (H 2 O) 4 ⁇ 8H 2 O is preferable.
• the inorganic fiber material a commercially available material may be used, or a material produced by a known production method may be used.
• Specific examples of the inorganic fiber material include, for example, inorganic fiber materials manufactured and sold by Ube Material Industries, Ltd., Otsuka Chemical Co., Ltd., Shikoku Chemicals Corporation, Omi Mining Co., Ltd., etc.
• a content of the inorganic fiber material based on 100 parts by mass of the rubber component is preferably 1.0 part by mass or more, more preferably 1.5 parts by mass or more, further preferably 2.0 parts by mass or more, particularly preferably 2.5 parts by mass or more, from the viewpoint of anisotropy of the rubber composition. Moreover, it is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, further preferably 40 parts by mass or less, particularly preferably 30 parts by mass or less, from the viewpoint of breaking strength of the rubber composition.
• An average diameter (also referred to as an average fiber diameter or an average width) D of the inorganic fiber material is preferably 1.0 nm or more, more preferably 2.0 nm or more, further preferably 3.0 nm or more, from the viewpoints of rigidity and processability of the rubber composition. Moreover, it is preferably 2000 nm or less, more preferably 1000 nm or less, further preferably 500 nm or less, particularly preferably 100 nm or less, from the viewpoints of rigidity and breaking strength of the rubber composition.
• An average length (also referred to as an average fiber length) L of the inorganic fiber material is preferably 0.10 ⁇ m or more, more preferably 0.15 ⁇ m or more, further preferably 0.20 ⁇ m or more, particularly preferably 0.50 ⁇ m or more, from the viewpoint of anisotropy of the rubber composition. Moreover, it is preferably 100 ⁇ m or less, more preferably 80 ⁇ m or less, further preferably 60 ⁇ m or less, particularly preferably 40 ⁇ m or less, from the viewpoints of rigidity and breaking strength of the rubber composition.
• the average diameter D and the average length L can be measured by image analysis of scanning electron micrographs, image analysis of transmission micrographs, analysis of X-ray scattering data, a pore electrical resistance method (Coulter principle), and the like.
• An aspect ratio L/D of the inorganic fiber material is preferably 2 or more, more preferably 4 or more, further preferably 6 or more, particularly preferably 8 or more, from the viewpoint of anisotropy of the rubber composition. Moreover, it is preferably 1000 or less, more preferably 500 or less, further preferably 250 or less, particularly preferably 100 or less, from the viewpoint of breaking strength of the rubber composition.
• the rubber composition according to the present disclosure comprises a coupling agent.
• the inorganic fiber material is less likely to be dispersed in the rubber component compared with a filler such as carbon black, but dispersibility of the inorganic fiber material is improved by compounding a coupling agent, which also improves anisotropy.
• the coupling agent that can be used in the present disclosure is not particularly limited, examples of which include a silane coupling agent that couples with silica and a rubber component, a carbon coupling agent that couples with carbon black and a rubber component, and the like.
• the silane coupling agent is not particularly limited, and a silane coupling agent conventionally used in combination with silica in the rubber industry can be used, examples of which include, for example, silane coupling agents having mercapto groups described below; silane coupling agents having sulfide groups such as bis(3-triethoxysilylpropyl)disulfide and bis(3-triethoxysilylpropyl)tetrasulfide; silane coupling agents having vinyl gorups such as vinyltriethoxysilane and vinyltrimethoxysilane; silane coupling agents having amino groups such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and 3-(2-aminoethyl)aminopropyltriethoxysilane; glycidoxy-based silane coupling agents such as ⁇ -glycidoxypropyltriethoxysilane and ⁇ -glycidoxypropy
• silane coupling agents having sulfide groups and/or silane coupling agents having mercapto groups are preferable, and silane coupling agents having sulfide groups are more preferable.
• These silane coupling agents may be used alone, or two or more thereof may be used in combination.
• the silane coupling agent having a mercapto group is a compound represented by the following formula (1) and/or a compound comprising a bond unit A represented by the following formula (2) and a bond unit B represented by the following formula (3).
• R 101 , R 102 , and R 103 each independently represents a group represented by an alkyl having 1 to 12 carbon atoms, an alkoxy having 1 to 12 carbon atoms, or -O-(R 111 -O) z -R 112 (R 111 s of z pieces each independently represents a divalent hydrocarbon group having 1 to 30 carbon atoms; R 112 represents an alkyl having 1 to 30 carbon atoms, an alkenyl having 2 to 30 carbon atoms, an aryl having 6 to 30 carbon atoms, or an aralkyl having 7 to 30 carbon atoms; and z represents an integer of 1 to 30); and R 104 represents an alkylene having 1 to 6 carbon atoms.
• Examples of the compound represented by the chemical formula (1) include, for example, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, a compound represented by the following chemical formula (4) (Si363 manufactured by Evonik Degussa GmbH), and the like.
• the compound represented by the following chemical formula (4) can be appropriately used. They may be used alone, or two or more thereof may be used in combination.
• Examples of the compound comprising the bond unit A represented by the formula (2) and the bond unit B represented by the formula (3) include, for example, those manufactured and sold by Momentive Performance Materials, etc. They may be used alone, or two or more thereof may be used in combination.
• the carbon coupling agent is not particularly limited, and examples thereof include tetrasulfide compounds such as bis(dimethylaminoethyl) tetrasulfide (DME) and bis(dimethylaminopropyl) tetrasulfide (DMP); benzimidazole-based compounds such as 1,2-bis(benzimidazolyl-2) ethane (EBZ) and 1,4'-bis(mercaptobenzimidazolyl-2) butane (C4SBZ); pyrithion metal salts, and the like. These carbon coupling agents may be used alone, or two or more thereof may be used in combination.
• DME bis(dimethylaminoethyl) tetrasulfide
• DMP bis(dimethylaminopropyl) tetrasulfide
• benzimidazole-based compounds such as 1,2-bis(benzimidazolyl-2) ethane (EBZ) and 1,4'
• a content of the coupling agent (preferably silane coupling agent) based on 100 parts by mass of the rubber component is preferably 1.0 part by mass or more, more preferably 1.5 parts by mass or more, further preferably 2.0 parts by mass or more, from the viewpoint of enhancing dispersibility of the inorganic fiber material. Moreover, it is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, further preferably 20 parts by mass or less, particularly preferably 15 parts by mass or less, from the viewpoint of breaking strength.
• a content of the inorganic fiber material based on 100 parts by mass of the rubber component is defined as A (part by mass)
• a content of silica based on 100 parts by mass of the rubber component is defined as B (part by mass)
• a content of the coupling agent (preferably silane coupling agent) based on 100 parts by mass of the rubber component is defined as X (part by mass)
• A, B, and X satisfy the following inequality (5): 0.09 A + 0.08 B ⁇ X ⁇ 0 .35A + 0.08 B
• the rubber composition as a filler, those commonly used in the conventional rubber industry can be compounded, such as carbon black, silica, aluminum hydroxide, calcium carbonate, alumina, clay, and talc.
• the rubber composition preferably comprises carbon black, more preferably comprises carbon black and silica.
• carbon black Since carbon black has high heat generation during mixing, it is considered that it promotes plasticization during mixing, and that the inorganic fiber material reacts with the coupling agent, allowing for carbon black to become easy to be dispersed in the rubber matrix. At the same time, unlike the inorganic fiber material, since carbon black can obtain a reinforcing effect without having anisotropy, the least breaking strength required can be imparted in the cross-grain direction of the inorganic fiber. On the other hand, although silica is inferior in reinforcing effect to carbon black and the inorganic fiber material, it can supplely exhibit a reinforcing effect, so that it is considered to be able to reinforce the entire rubber matrix while ensuring suppleness in the cross-grain direction.
• Carbon black is not particularly limited, and those common in the tire industry can be used such as GPF, FEF, HAF, ISAF, and SAF, and specifically, N110, N115, N120, N125, N134, N135, N219, N220, N231, N234, N293, N299, N326, N330, N339, N343, N347, N351, N356, N358, N375, N539, N550, N582, N630, N642, N650, N660, N683, N754, N762, N765, N772, N774, N787, N907, N908, N990, N991, and the like can be appropriately used, and in-house synthesized products and the like can also be appropriately used. These carbon black may be used alone, or two or more thereof may be used in combination.
• a nitrogen adsorption specific surface area (N 2 SA) of carbon black is preferably 30 m 2 /g or more, more preferably 35 m 2 /g or more, further preferably 40 m 2 /g or more, from the viewpoints of weather resistance and reinforcing property. Moreover, it is preferably 250 m 2 /g or less, more preferably 220 m 2 /g or less, from the viewpoints of dispersibility, fuel efficiency, fracture characteristics, and durability.
• N 2 SA of carbon black in the present specification is a value measured according to JIS K 6217-2: 2017 "Carbon black for rubber industry-Fundamental characteristics-Part 2: Determination of specific surface area-Nitrogen adsorption methods-Single-point procedures" A Method.
• a cetyltrimethylammonium bromide adsorption specific surface area (CTAB) of carbon black is preferably 180 m 2 /g or less, more preferably 165 m 2 /g, further preferably 150 m 2 /g or less, from the viewpoint of securing anisotropy of the rubber composition without excessively strengthening a rubber network.
• a lower limit value of the CTAB of carbon black is, but not particularly limited to, preferably 30 m 2 /g or more, more preferably 40 m 2 /g or more, further preferably 50 m 2 /g or more, from the viewpoint of reinforcing property.
• the CTAB is a value that correlates with a particle size of carbon black, representing that the larger the CTAB is, the smaller the particle size of carbon black is.
• the CTAB of carbon black in the present specification is a value measured according to JIS K 6217-3: 2001 "Carbon black for rubber industry-Fundamental characteristics-Part 3: Determination of specific surface area-CTAB adsorption methods".
• a content of carbon black when compounded based on 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 5 parts by mass or more, further preferably 10 parts by mass or more, particularly preferably 15 parts by mass or more, from the viewpoints of weather resistance and reinforcing property. Moreover, it is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, further preferably 60 parts by mass or less, from the viewpoint of fuel efficiency.
• Silica is not particularly limited, and those common in the tire industry can be used, such as, for example, silica prepared by a dry process (anhydrous silica) and silica prepared by a wet process (hydrous silica). Among them, hydrous silica prepared by a wet process is preferable from the reason that it has many silanol groups. These silica may be used alone, or two or more thereof may be used in combination.
• a nitrogen adsorption specific surface area (N 2 SA) of silica is preferably 140 m 2 /g or more, more preferably 150 m 2 /g or more, further preferably 160 m 2 /g or more, particularly preferably 170 m 2 /g or more, from the viewpoints of fuel efficiency and abrasion resistance. Moreover, it is preferably 350 m 2 /g or less, more preferably 300 m 2 /g or less, further preferably 250 m 2 /g or less, from the viewpoints of fuel efficiency and processability.
• the N 2 SA of silica in the present specification is a value measured by a BET method according to ASTM D3037-93.
• a content of silica when compounded based on 100 parts by mass of the rubber component is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, further preferably 15 parts by mass or more, particularly preferably 20 parts by mass or more, from the viewpoint of fuel efficiency. Moreover, it is preferably 110 parts by mass or less, more preferably 100 parts by mass or less, further preferably 90 parts by mass or less, particularly preferably 80 parts by mass or less, from the viewpoint of processability.
• a total content of silica and carbon black based on 100 parts by mass of the rubber component is preferably 20 parts by mass or more, more preferably 25 parts by mass or more, further preferably 30 parts by mass or more, particularly preferably 35 parts by mass or more, from the viewpoint of reinforcing property. Moreover, it is preferably 200 parts by mass or less, more preferably 170 parts by mass or less, further preferably 150 parts by mass or less, particularly preferably 130 parts by mass or less, from the viewpoint of processability.
• a content of silica in the total content of silica and carbon black is preferably 50% or more, more preferably 70% or more, further preferably 80% or more.
• a content of the inorganic fiber material in a total content of the inorganic fiber material, silica, and carbon black is preferably 5% by mass or more, more preferably 8% by mass or more. This makes it easier to obtain an anisotropy effect of the inorganic fiber material.
• the content of the inorganic fiber material in the total content of the inorganic fiber material, silica, and carbon black is preferably 30% by mass or less, more preferably 25% by mass or less, further preferably 20% by mass or less. This makes a rubber phase to be reinforced only in the grain direction, allowing for preventing strength from becoming extremely weak in the cross-grain direction.
• the rubber composition can appropriately comprise compounding agents conventionally and generally used in the tire industry, for example, a plasticizer, wax, an antioxidant, stearic acid, zinc oxide, a vulcanizing agent such as sulfur, a vulcanization accelerator, and the like, in addition to the above-described components.
• a plasticizer By comprising a plasticizer, viscosity of a rubber is lowered at the time of mixing, making inorganic fiber materials easily dispersed, so that anisotropy and breaking strength tend to be improved.
• the plasticizer include, for example, oil, a resin component, a liquid rubber, and the like.
• oil examples include, for example, mineral oils such as aromatic oils, process oils, and paraffin oils, and the like. Among them, it is preferable to use process oils because they reduce burden on the environment.
• a content of oil when compounded based on 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, further preferably 5 parts by mass or more, particularly preferably 7 parts by mass or more, from the viewpoint of processability. Moreover, it is preferably 80 parts by mass or less, more preferably 70 parts by mass or less, further preferably 60 parts by mass or less, particularly preferably 50 parts by mass or less, from the viewpoint of abrasion resistance. Besides, in the present specification, the content of oil also includes an amount of oil contained in an oil-extended rubber.
• the resin component is not particularly limited, examples of which include a petroleum resin, a terpene-based resin, a rosin-based resin, a phenol-based resin, and the like, which are commonly used in the tire industry.
• the petroleum resin include a C5-based petroleum resin, an aromatic-based petroleum resin, a C5-C9-based petroleum resin, and the like. These resin components may be used alone, or two or more thereof may be used in combination.
• a "C5-based petroleum resin” refers to a resin obtained by polymerizing a C5 fraction.
• the C5 fraction include, for example, a petroleum fraction having 4 to 5 carbon atoms such as cyclopentadiene, pentene, pentadiene, and isoprene.
• a dicyclopentadiene resin DCPD resin
• DCPD resin dicyclopentadiene resin
• the "aromatic-based petroleum resin” refers to a resin obtained by polymerizing a C9 fraction, and may be hydrogenated or modified.
• the C9 fraction include, for example, a petroleum fraction corresponding to 8 to 10 carbon atoms such as vinyltoluene, alkylstyrene, indene, and methyl indene.
• the aromatic-based petroleum resin for example, a coumarone indene resin, a coumarone resin, an indene resin, and an aromatic vinyl-based resin are appropriately used.
• aromatic vinyl-based resin a homopolymer of ⁇ -methylstyrene or styrene or a copolymer of ⁇ -methylstyrene and styrene is preferable, and a copolymer of ⁇ -methylstyrene and styrene is more preferable, because it is economical, easy to process, and excellent in heat generation.
• aromatic vinyl-based resin for example, those commercially available from Kraton Corporation, Eastman Chemical Company, etc. can be used.
• C5-C9-based petroleum resin refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and may be hydrogenated or modified.
• Examples of the C5 fraction and the C9 fraction include the above-described petroleum fractions.
• a C5-C9-based petroleum resin those commercially available from, for example, Tosoh Corporation, Zibo Luhua Hongjin New Material Co., Ltd., etc. can be appropriately used.
• terpene-based resin examples include a polyterpene resin consisting of at least one selected from terpene compounds such as ⁇ -pinene, ⁇ -pinene, limonene, and a dipentene; an aromatic-modified terpene resin made from the terpene compound and an aromatic compound; a terpene phenol resin made from a terpene compound and a phenol-based compound; and those in which these terpene-based resins are hydrogenated (hydrogenated terpene-based resins).
• Examples of the aromatic compound used as a raw material for the aromatic-modified terpene resin include, for example, styrene, ⁇ -methylstyrene, vinyltoluene, a divinyltoluene, and the like.
• Examples of the phenol-based compound used as a raw material for the terpene phenol resin include, for example, phenol, bisphenol A, cresol, xylenol, and the like.
• Example of the rosin-based resin include, but not particularly limited to, for example, a natural resin rosin and a rosin-modified resin obtained by modifying it by hydrogenation, disproportionation, dimerization, esterification, or the like.
• phenol-based resin examples include, but not particularly limited to, a phenol formaldehyde resin, an alkylphenol formaldehyde resin, an alkylphenol acetylene resin, an oil-modified phenol formaldehyde resin, and the like.
• a content of the resin component when compounded based on 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, further preferably 5 parts by mass or more. Moreover, the content of the resin component is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, further preferably 20 parts by mass or less.
• the liquid rubber is not particularly limited as long as it is a polymer in a liquid state at a normal temperature (25°C), examples of which include, for example, a liquid butadiene rubber (a liquid BR), a liquid styrene-butadiene rubber (a liquid SBR), a liquid isoprene rubber (a liquid IR), a liquid styrene-isoprene rubber (a liquid SIR), a liquid farnesene rubber, and the like. These liquid rubbers may be used alone, or two or more thereof may be used in combination.
• a content of the liquid rubber when compounded based on 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, further preferably 5 parts by mass or more. Moreover, the content of the liquid rubber is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, further preferably 20 parts by mass or less.
• a content of the plasticizer based on 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, further preferably 5 parts by mass or more, particularly preferably 7 parts by mass or more.
• the content of the plasticizer is preferably 90 parts by mass or less, more preferably 70 parts by mass or less, further preferably 50 parts by mass or less, particularly preferably 30 parts by mass or less.
• a content of wax when compounded based on 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, further preferably 1.5 parts by mass or more, from the viewpoint of weather resistance of a rubber. Moreover, it is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, from the viewpoint of preventing whitening of a tire due to bloom.
• antioxidants include, but not particularly limited to, for example, amine-based, quinoline-based, quinone-based, phenol-based, and imidazole-based compounds, and antioxidants such as a carbamic acid metal salt, preferably, phenylenediamine-based antioxidants such as N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N-isopropyl-N'-phenyl-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine, N,N'-di-2-naphthyl-p-phenylenediamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine, N,N'-bis(1-methylheptyl)-p-phenylenediamine, N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine, N,
• a content of the antioxidant when compounded based on 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, further preferably 1.5 parts by mass or more, from the viewpoint of ozone crack resistance of a rubber. Moreover, it is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, from the viewpoints of abrasion resistance and wet grip performance.
• a content of stearic acid when compounded based on 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, further preferably 1.5 parts by mass or more, from the viewpoint of processability. Moreover, it is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, from the viewpoint of vulcanization rate.
• a content of zinc oxide when compounded based on 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, further preferably 1.5 parts by mass or more, from the viewpoint of processability. Moreover, it is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, from the viewpoint of abrasion resistance.
• Sulfur is appropriately used as a vulcanizing agent.
• sulfur a powdery sulfur, an oil processing sulfur, a precipitated sulfur, a colloidal sulfur, an insoluble sulfur, a highly dispersible sulfur, and the like can be used.
• a content of sulfur when compounded as a vulcanizing agent based on 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, further preferably 1.5 part by mass or more, from the viewpoints of securing a sufficient vulcanization reaction and obtaining good grip performance and abrasion resistance. Moreover, it is preferably 5.0 parts by mass or less, more preferably 4.5 parts by mass or less, further preferably 4.0 parts by mass or less, from the viewpoint of preventing deterioration.
• vulcanizing agents other than sulfur include, for example, vulcanizing agents comprising a sulfur atom such as TACKIROL V-200 manufactured by Taoka Chemical Co., Ltd., DURALINK HTS (sodium hexamethylene-1,6-bisthiosulfate dihydrate) manufactured by Flexsys, and KA9188 (1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane) manufactured by LANXESS, organic peroxides such as dicumyl peroxide, and the like.
• a sulfur atom such as TACKIROL V-200 manufactured by Taoka Chemical Co., Ltd.
• DURALINK HTS sodium hexamethylene-1,6-bisthiosulfate dihydrate
• Flexsys and KA9188 (1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane
• organic peroxides such as
• vulcanization accelerator examples include, but not particularly limited to, for example, sulfenamide-based, thiazole-based, thiuram-based, thiourea-based, guanidine-based, dithiocarbamic acid-based, aldehyde-amine-based or aldehyde-ammonia-based, imidazoline-based, and xanthate-based vulcanization accelerators.
• sulfenamide-based vulcanization accelerators and guanidine-based vulcanization accelerators are preferable, and it is more preferable to use two of them in combination, from the viewpoint that desired effects can be obtained more appropriately.
• Examples of the sulfenamide-based vulcanization accelerator include CBS (N-cyclohexyl-2-benzothiazolyl sulfenamide), TBBS (N-t-butyl-2-benzothiazolyl sulfenamide), N-oxyethylene-2-benzothiazolyl sulfenamide, N,N'-diisopropyl-2-benzothiazolyl sulfenamide, N,N-dicyclohexyl-2-benzothiazolyl sulfenamide, and the like.
• Examples of the thiazole-based vulcanization accelerator include 2-mercaptobenzothiazole, dibenzothiazolyl disulfide, and the like.
• Examples of the thiuram-based vulcanization accelerator include tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetrabenzylthiuram disulfide (TBzTD), and the like.
• Examples of the guanidine-based vulcanization accelerator include 1,3-diphenylguanidine (DPG), diorthotrilguanidine, orthotrilbiguanidine, and the like. These vulcanization accelerators may be used alone, or two or more thereof may be used in combination.
• a content of the vulcanization accelerator when compounded based on 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, further preferably 1.5 parts by mass or more.
• the content of the vulcanization accelerator based on 100 parts by mass of the rubber component is preferably 8 parts by mass or less, more preferably 7 parts by mass or less, further preferably 6 parts by mass or less.
• the rubber composition of the present disclosure can be produced by a known method, for example, by a method of kneading components other than vulcanizing agents and vulcanization accelerators, of the above-described components, with a known kneading machine used in the general rubber industry such as a Banbury mixer, a kneader, and an open roll, then adding the vulcanizing agents and the vulcanization accelerators to the mixture to further knead them, and then vulcanizing them, and the like.
• a known kneading machine used in the general rubber industry such as a Banbury mixer, a kneader, and an open roll
• kneading is performed at 80°C to 170°C for 1 to 30 minutes
• vulcanization is performed at 130°C to 190°C for 3 to 20 minutes.
• the rubber composition of the present disclosure realizes a supple response to an input (vibration) from a tire vertical direction during rolling by orienting the inorganic fibers in the tire circumferential direction and improves in responsiveness to the input during steering by increasing rigidity in the orientation direction (tire circumferential direction). Therefore, it can be appropriately used for continuous members in the tire circumferential direction such as a cap tread, a base tread, a sidewall, a sidewall inner layer, an inner liner, a strip apex, a bead apex, a clinch apex, a bead reinforcement layer, an insulation, and an insert, and it is considered that the similar effect can be obtained in either case.
• a rubber composition for tire internal member such as a base tread, a sidewall inner layer, an inner liner, a strip apex, a bead apex, a bead reinforcing layer, an insulation, and an insert.
• elasticity (responsiveness) of the tire in the rolling direction can be improved while maintaining cushioning property, so that it is considered that steering stability and ride comfort are improved.
• the "internal member” is not limited to the above-described members, but shall refer to tire members other than members that form an outer surface when the tires are mounted on a rim and filled with air.
• the tire of the present disclosure can be produced by a usual method using the above-described rubber composition. That is, an unvulcanized rubber composition, in which each of the above-described components is compounded as necessary with the rubber component, is extruded into a shape of a corresponding tire member to obtain a rubber composition in which inorganic fiber materials are oriented in a grain direction. Then, the above-described rubber composition is attached together with other tire members on a tire molding machine so that the inorganic fiber materials are oriented in a tire circumferential direction, and the mixture is molded by a usual method to form an unvulcanized tire, and this unvulcanized tire is heated and pressurized in a vulcanizing machine, thereby producing a tire.
• the tire of the present disclosure may be a pneumatic tire or a non-pneumatic tire. Moreover, it is appropriate for a racing tire, a tire for a passenger car, a tire for a large passenger car, a tire for a large SUV, or a tire for a motorcycle, and can be used as a summer tire, a winter tire, or a studless tire thereof.
• the above-described unvulcanized rubber composition was extruded into a shape of a sidewall inner layer with an extruder equipped with a mouthpiece having a predetermined shape to obtain a sidewall inner layer in which inorganic fiber materials were oriented in a grain direction. Then, the above-described sidewall inner layer was attached together with other tire members on the tire molding machine so that the inorganic fiber materials were oriented in the tire circumferential direction to form an unvulcanized tire, and this unvulcanized tire was press-vulcanized under a condition at 170°C for 12 minutes to produce a tire (size: 205/65R15).
• the above-described vulcanized rubber sheet was punched in a grain direction (a roll rotation direction when producing an unvulcanized rubber sheet before vulcanization) with a JIS No. 3 dumbbell, and a tensile stress at 100% elongation (M100a) in the grain direction was measured under a condition of a tensile speed at 500 mm/min according to JIS K 6251: 2017. Similarly, the vulcanized rubber sheet was punched in a cross-grain direction (a direction perpendicular from the roll rotation direction when producing an unvulcanized rubber sheet before vulcanization) with the JIS No.
• breaking strength EB ⁇ TB/2
• This tire was mounted to a car with a displacement of 2000 cc.
• This car was run on a test course having an asphalt road surface, and sensory evaluations on ride comfort and stability of control during steering (steering stability) were performed by a test driver.
• the evaluations were performed on a scale of 10 points, where relative evaluations were performed with the reference Comparative example being as 6.0 points. The results show that the higher the score is, the better the steering stability and ride comfort are.
• the rubber composition of the present disclosure comprising an inorganic fiber material and a coupling agent can highly achieve both breaking strength and anisotropy. Moreover, it can be found that the tire of the present disclosure comprising the tire internal member formed of the rubber composition has improved ride comfort and steering stability with a good balance.

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• 2020
  • 2020-10-19 EP EP20888238.1A patent/EP4015236A4/de active Pending
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